The proposal to buy HPCL’s stake at Rs 37.75 per share has been sent to the petroleum ministry for its approval. If approved, ONGC stake in MRPL will climb to 87.95 per cent, sources said. MRPL would continue as ONGC's subsidiary for the time being, they added.

ONGC’s investment has seen MRPL scrip zoom from Rs 6 to Rs 37 on the stock exchanges.

Incidentally, this move by ONGC, which has diversified into refining and is planning a foray into retail marketing of petroleum products, comes at a time when HPCL is undecided about selling its stake in MRPL.